Full closed-loop green regeneration and recycling technology for spent ternary lithium batteries: Hydrogen reduction with sulfuric acid cycle -leaching process

With the rapid growth in demand and capacity of lithium-ion batteries (LIBs), a large number of spent LIBs with the dual attributes of hazardous waste and high value-added resources have also experienced a spurt in retirement. In this paper, a process of hydrogen reduction - water-leaching to recover Li – H₂SO₄ cycle-leaching to recover Ni/Co/Mn to regenerate ternary cathode (NCM) precursor was used to treat mixed spent NCM, and its recovery mechanism was investigated. Under the optimal conditions, Li was completely converted into readily-soluble LiOH by hydrogen reduction and then recovered by water-leaching and CO₂ precipitation to regenerate high-purity Li₂CO₃. While Ni/Co/Mn was reduced to low-valent and could basically be completely leached by H₂SO₄ and the H₂SO₄-leaching solution could be cycled to leach Ni/Co/Mn after supplementing with some H₂SO₄. When the cycle time reached 5, the concentrations of Ni/Co/Mn reached 144.79 g/L, 100.01 g/L, 113.39 g/L, respectively. Finally, a few solids that could not be completely dissolved due to the cycle were leached out by H₂SO₄ and mixed with the cycle-leaching solution to regenerate the NCM precursor with high-purity and excellent performance for direct commercial application by coprecipitation.